In a semiconductor fabrication process, various vacuum processes such as film deposition, etching, and the like are carried out. In processing apparatuses for carrying out such vacuum processes, a semiconductor wafer to be processed is transferred into a chamber the inside of which is evacuatable to vacuum, and the chamber is evacuated to vacuum by an evacuation apparatus including a vacuum pump, thereby carrying out a predetermined process on the semiconductor wafer.
During the process, the chamber is evacuated by the vacuum pump, and an inner pressure of the chamber is controlled by adjusting an opening degree of a pressure control valve provided between the chamber and the vacuum pump. Such pressure control valves are described, for example, in Patent Document 1 (Japanese Patent Laid-Open Publication No. H09-178000) and Patent Document 2 (Japanese Patent Laid-Open Publication No. 2005-9678. The pressure control valves described in these documents are configured so that a circular plate valve element is provided at the distal end of an arm extending from a pivot shaft, and the pivot shaft is pivoted to allow the valve element to move from a position where the valve element closes a flow passage to another position where the valve element fully opens the flow passage.
The pressure control valves described in Patent Documents 1 and 2 are provided in a valve body with two openings that provide a fluid passage and a space that houses the circular plate valve element, the space being provided in a direction intersecting the fluid passage. The circular plate valve element is integrally provided at the distal end of the pivot shaft arm. When the pressure control valve is fully open, the circular plate element is positioned inside the space. Namely, the element is positioned sideways to the fluid passage, and thus the openings are fully opened.
On the other hand, when the element is moved to a position where the openings are completely covered by the valve element, a sealing member attached on the valve element is not in firm contact with the openings, and does not completely seal the openings. In order for the valve element to seal the opening, a cylinder-shaped sealing joint member is moved along a shaft direction to press the sealing member of the element toward the opening, thereby sealing the opening.
Incidentally, Patent Document 3 describes a gate valve configured so that a flow rate controlling portion for controlling an inner pressure in a chamber, for example, including a vane and a slidable resistive element is provided in an evacuation passage and a main valve seal (sealing member) provided in a main valve element is blocked off from radicals and plasma in an evacuation gas.
Patent Document 1: Japanese Patent Application Laid-Open Publication No. H09-178000.
Patent Document 2: Japanese Patent Application Laid-Open Publication No. 2005-9678.
Patent Document 3: Japanese Patent Application Laid-Open Publication No. 2004-286131.